The MacArthur Fellow and short-story writer George Saunders, in a recent piece on Trumpism, wrote “I’ve never before imagined America as fragile, as an experiment that could, within my very lifetime, fail. But I imagine it that way now.” I’m a bit older than George Saunders, and so was in the generation that was taught in grade-school civics about “the American experiment.” This was, I suppose, designed to motivate us children to take on the burdens of citizenship. The outcome of the “experiment,” we were taught, was very much up in the air, and largely depended on us.

As a result, I still regard the promise of America as a hypothesis. It was tested by slavery, fascism, and communism, and I believe that further tests will follow. Trumpism is one of them. And there is nothing written in the stars that says we must pass.

Our founding fathers had a great fear of democracy, which all too often had resulted in one tyranny being replaced with another. So they tried an experiment. Foreseeing the dangers of demagogic populism, they established a more limited type of democracy, a constitutional democracy, where the passions of the people were, at every turn, tested, tempered and slowed by a multi-polar government and a framework of fundamental rights that could not be denied, even at the behest of the majority of the citizenry.

Some people who plan to hold their noses and vote for Mr. Trump acknowledge that much of his core program (such as a religious test for admittance to the country) is both morally repugnant and illegal. But they argue, it’s really OK, because Trump will be stopped from implementing his worst ideas by our system of constitutional checks and balances. For example, the New York Times quoted Senator John McCain (before he withdrew his support for Mr. Trump) as saying that he did not believe that the nation would be in danger under a Trump presidency: “I still believe we have the institutions of government that would restrain someone who seeks to exceed their constitutional obligations,” Mr. McCain said. “We have a Congress. We have the Supreme Court. We’re not Romania.”

I respectfully disagree with this line of thinking. In my novel Christian Nation, I used the counterfactual of a Sarah Palin presidency to probe the strength of our democracy in the face of severe economic distress, a second major terrorist attack, and the simultaneous rise of a populist demagogue. My careful analysis of constitutional law and political strategy convinced me that the nation could fail that test.

One reason is that the effectiveness of our constitutional architecture is predicated on certain social and cultural conditions:

belief in and respect for human dignity

trust in the integrity of the system and its institutions

acceptance of the rule of law, and

maintenance of a minimum educational standard.

To judge the risk to our democracy posed by Trumpism, we need to assess the strength of these foundations. It is a mixed picture. The advances we have made in civil rights for women, African-Americans, LGBT people, and disabled citizens demonstrate a common and growing commitment to human dignity. (I believe this to be true notwithstanding the racism and misogyny of some of Trumps’ most ardent supporters because, despite the voice given them by Mr. Trump, they are a shrinking minority.) More troubling, however, is the fact that Americans saying they trust the institutions of government fell from almost 80% in 1965 to only 19% this year. And international rankings of America’s educational performance (24th in reading, 36th in math) would throw Thomas Jefferson ("An educated citizenry is a vital requisite for our survival as a free people.") into despair. It is undeniable that the foundation necessary for our constitutional democracy to endure a challenge like Trumpism is, like the country itself, deeply fractured.

Commentators on both the left and the right have reached the same conclusion. Adam Gopnik argues “Those who think that the underlying institutions of American government are immunized against [fascism] fail to understand history. In every historical situation where a leader of Trump’s kind come to power, normal safeguards collapse.” David Brooks agrees: “As the founders would have understood, he is a threat to the long and glorious experiment of American self-government. He is precisely the kind of scapegoating, promise-making, fear-driving demagogue they feared.” Just when our constitutional democracy may be put to a great test, we find that democracy greatly weakened by a popular loss of trust in its institutions, a debased popular culture, and the chronic failures of our system of education.

No matter how deep your antipathy toward Secretary Clinton, refocusing on the idea of “the American experiment” and the fragility of our republic offers an instructive perspective on your choice. Adam Gopnik put it best: “No reasonable person, no matter how opposed to her politics, can believe for a second that Clinton’s accession to power would be a threat to the Constitution or the continuation of American democracy. No reasonable person can believe that Trump’s accession to power would not be.”

A note on recent developments: So the Billy Bush video showed Trump to be a vulgar misogynist. This is hardly a surprise. Nor does it rank in the top group of reasons that Trump must not become president. It is deeply unsettling that it took an accidental video, and one dealing with sex, to push responsible Republican leaders over the line. The real scandal is that they were willing to overlook his crippling and delusional narcissism, ignorance, lack of skill or temperament to do the job, proto-fascist demonization of immigrants and Muslims, racism, disrespect for the constitution and rule of law, not to mention fantastical and bizarre ideas about policy (build The Wall, take the oil, get the jobs back from China, etc., etc.). And it is doubly unsettling that this all resulted in the second “debate” sinking to new lows of ugly meaninglessness. Trump has dragged us all into the sewer where he reigns as self-professed King, and I for one awoke this morning feeling dirty and in deep despair for my beloved country.